Implant with deployable blades

ABSTRACT

An implant is described for use in the spine, including two blades attached to a blade actuating member. Each blade includes a protruding portion that engages a corresponding channel in the blade actuating member. The blade or blades are extended or retracted when the blade actuating member is translated along a first axis. Each blade is retained in channels within the blade actuating member, and channels within the body of the implant, that constrain each blade to move in a direction near perpendicular to the direction of motion of the blade actuating member.

BACKGROUND

The embodiments are generally directed to implants for supporting bonegrowth in a patient.

A variety of different implants are used in the body. Implants used inthe body to stabilize an area and promote bone ingrowth provide bothstability (i.e. minimal deformation under pressure over time) and spacefor bone ingrowth.

Spinal fusion, also known as spondylodesis or spondylosyndesis, is asurgical treatment method used for the treatment of various morbiditiessuch as degenerative disc disease, spondylolisthesis (slippage of avertebra), spinal stenosis, scoliosis, fracture, infection or tumor. Theaim of the spinal fusion procedure is to reduce instability and thuspain.

In preparation for the spinal fusion, most of the intervertebral disc isremoved. An implant, the spinal fusion cage, may be placed between thevertebra to maintain spine alignment and disc height. The fusion (i.e.bone bridge) occurs between the endplates of the vertebrae.

SUMMARY

In one aspect, an implant includes a body with a first axis. The implantalso includes a blade having a retracted position in the body and anextended position where the blade extends outwardly from the body. Theimplant also includes a blade actuating member that can translatethrough the body in directions parallel to the first axis. The bladeactuating member includes a channel, where the channel extends between asuperior surface and an inferior surface of the blade actuating member,and where the channel defines a first channel direction and an opposingsecond channel direction. The blade includes a protruding portionconfigured to fit within the channel. When the blade actuating member ismoved in a first direction along the first axis, the protruding portionfollows the channel in the first channel direction and the blade movestowards the extended position. When the blade actuating member is movedin a second direction opposite the first direction, the protrudingportion follows the channel in the second channel direction and theblade moves towards the retracted position.

In another aspect, an implant includes a body having a first axis. Theimplant also includes a blade having a retracted position in the bodyand an extended position where the blade extends outwardly from thebody. The blade has an outer edge, an inner edge, a first lateral edgeand a second lateral edge. The first lateral edge of the blade and thesecond lateral edge of the blade are in contact with the body. The bladealso has a distal face and a proximal face. The implant includes a bladeactuating member that can translate through the body in directionsparallel to the first axis. A portion of the proximal face is in contactwith the blade actuating member. The distal face is disposed away fromthe body. The blade actuating member can move the blade between theretracted position and the extended position.

In another aspect, an implant includes an outer structure having a firstaxis. The implant also includes a blade having a retracted position inthe outer structure and an extended position where the blade extendsoutwardly from the outer structure. The implant also includes a bladeactuating member that can translate through the outer structure indirections parallel to the first axis. The blade actuating member iscoupled to the blade and can move the blade between the retractedposition and the extended position. The outer structure includes a firstend having a threaded opening and a guide opening adjacent the threadedopening, where the guide opening receives a driven end of the bladeactuating member. The implant also includes a locking screw securedwithin the threaded opening. The locking screw can be rotated between anunlocked rotational position in which the driven end of the bladeactuating member can pass through the guide opening and a lockedrotational position, in which the drive end of the blade actuatingmember is prevented from moving through the guide opening.

Other systems, methods, features and advantages of the embodiments willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the embodiments, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, with emphasis instead being placed uponillustrating the principles of the embodiments. Moreover, in thefigures, like reference numerals designate corresponding partsthroughout the different views.

FIG. 1 is a schematic view of a spine with an implant, according to anembodiment;

FIG. 2 is an isometric view of an embodiment of an implant;

FIG. 3 is an exploded isometric view of the implant of FIG. 2;

FIG. 4 is a schematic isometric view of the implant of FIG. 2 in aninsertion position;

FIG. 5 is a lateral side view of the implant of FIG. 2 in the insertionposition;

FIG. 6 is a schematic isometric view of the implant of FIG. 2 in adeployed position;

FIG. 7 is a lateral side view of the implant of FIG. 2 in the deployedposition;

FIG. 8 is a schematic isometric view of an embodiment of a blade;

FIG. 9 is a schematic side view of an embodiment of a blade actuatingmember;

FIG. 10 is a schematic isometric view of an embodiment of a bladeactuating member and two corresponding blades;

FIG. 11 is a schematic isometric view of the blade actuating member ofFIG. 10 coupled with the two corresponding blades;

FIG. 12 is a schematic isometric view of an embodiment of a body for animplant;

FIG. 13 is a schematic isometric view of a distal side of a cap of animplant, according to an embodiment;

FIG. 14 is a schematic isometric view of a proximal side of the cap ofFIG. 13;

FIG. 15 is a schematic isometric view of body for an implant, accordingto another embodiment;

FIG. 16 is a top-down schematic view of an embodiment of an implant;

FIG. 17 is a top-down schematic view of a region of the implant of FIG.16;

FIG. 18 is a schematic isometric view of an implant in an insertionposition, including an enlarged cut-away view of several components,according to an embodiment;

FIG. 19 is a schematic isometric view of the implant of FIG. 18 in anintermediate position, including an enlarged cut away view of theseveral components;

FIG. 20 is a schematic isometric view of the implant of FIG. 18 in adeployed position, including an enlarged cut away view of the severalcomponents;

FIG. 21 is a schematic isometric view of the implant of FIG. 18 in anintermediate position, including an enlarged cut away view of theseveral components;

FIG. 22 is a schematic isometric view of a locking screw according to anembodiment;

FIG. 23 is a schematic side view of the locking screw of FIG. 22;

FIG. 24 is an isometric view of the locking screw of FIG. 22, includingan enlarged cut-away view of the locking screw;

FIG. 25 is a schematic isometric view of an implant with a locking screwin a rotational position that allows a blade actuating member to extendfrom an implant, according to an embodiment; and

FIG. 26 is a schematic isometric view of the implant of FIG. 25 in whichthe locking screw has been rotated to prevent the blade actuating memberfrom extending from the body of the implant.

DETAILED DESCRIPTION

The embodiments described herein are directed to an implant for use in aspine. The embodiments include implants with a body and one or moreblades. In addition to the various provisions discussed below, anyembodiments may make use of any of the body/support structures, blades,actuating members or other structures disclosed in Duffield et al., U.S.Pat. No. 9,707,100, issued on Jul. 18, 2017, currently U.S. patentapplication Ser. No. 15/194,323, filed on Jun. 27, 2016 and titled“Interbody Fusion Device and System for Implantation,” which is herebyincorporated by reference in its entirety. For purposes of convenience,the Duffield patent will be referred to throughout the application as“The Fusion Device Application”.

Introduction to the Implant

FIG. 1 is a schematic view of an embodiment of an implant 100. Implant100 may also be referred to as a cage or fusion device. In someembodiments, implant 100 is configured to be implanted within a portionof the human body. In some embodiments, implant 100 may be configuredfor implantation into the spine. In some embodiments, implant 100 may bea spinal fusion implant, or spinal fusion device, which is insertedbetween adjacent vertebrae to provide support and/or facilitate fusionbetween the vertebrae. For example, referring to FIG. 1, implant 100 hasbeen positioned between a first vertebra 192 and a second vertebra 194.Moreover, implant 100 is seen to include two blades (first blade 241 andsecond blade 242), which extend from the superior and inferior surfacesof implant 100. Each of the blades has been driven into an adjacentvertebra (i.e., first vertebra 192 or second vertebra 194) so as to helpanchor implant 100.

In some embodiments, implant 100 may be inserted using a lateralinterbody fusion (LIF) surgical procedure. In some cases, implant 100could be inserted through a small incision in the side of the body.Exemplary techniques that could be used include, but are not limited to:DLIF® (Direct Lateral Interbody Fusion), XLIF® (eXtreme LateralInterbody Fusion), and transpsoas interbody fusion.

For purposes of clarity, reference is made to various directionaladjectives throughout the detailed description and in the claims. Asused herein, the term “anterior” refers to a side or portion of animplant that is intended to be oriented towards the front of the humanbody when the implant has been placed in the body. Likewise, the term“posterior” refers to a side or portion of an implant that is intendedto be oriented towards the back of the human body followingimplantation. In addition, the term “superior” refers to a side orportion of an implant that is intended to be oriented towards a top(e.g., the head) of the body while “inferior” refers to a side orportion of an implant that is intended to be oriented towards a bottomof the body. Reference is also made herein to “lateral” sides orportions of an implant, which are sides or portions facing along alateral direction of the body.

FIG. 2 is a schematic isometric view of an embodiment of implant 100,according to an embodiment. As seen in FIG. 2, implant 100 is understoodto be configured with an anterior side 110 and a posterior side 112.Implant 100 may also include a first lateral side 114 and a secondlateral side 116. Furthermore, implant 100 may also include a superiorside 130 and an inferior side 140.

Reference is also made to directions or axes that are relative to theimplant itself, rather than to its intended orientation with regards tothe body. For example, the term “distal” refers to a part that islocated further from a center of an implant, while the term “proximal”refers to a part that is located closer to the center of the implant. Asused herein, the “center of the implant” could be the center of massand/or a central plane and/or another centrally located referencesurface.

An implant may also be associated with various axes. Referring to FIG.1, implant 100 may be associated with a longitudinal axis 120 thatextends along the longest dimension of implant 100 between first lateralside 114 and second lateral side 116. Additionally, implant 100 may beassociated with a posterior-anterior axis 122 (also referred to as a“widthwise axis”) that extends along the widthwise dimension of implant100, between posterior side 112 and anterior side 110. Moreover, implant100 may be associated with a vertical axis 124 that extends along thethickness dimension of implant 100 and which is generally perpendicularto both longitudinal axis 120 and posterior-anterior axis 122.

An implant may also be associated with various reference planes orsurfaces. As used herein, the term “median plane” refers to a verticalplane which passes from the anterior side to the posterior side of theimplant, dividing the implant into right and left halves, or lateralhalves. As used herein, the term “transverse plane” refers to ahorizontal plane located in the center of the implant that divides theimplant into superior and inferior halves. As used herein, the term“coronal plane” refers to a vertical plane located in the center of theimplant that divides the implant into anterior and posterior halves. Insome embodiments, the implant is symmetric about two planes, such as themedian and the transverse plane.

FIG. 3 is a schematic isometric exploded view of implant 100 accordingto an embodiment. Referring first to FIGS. 2-3, implant 100 is comprisedof a body 200 and a cap 220, which together may be referred to as outerstructure 201 of implant 100. In some embodiments, a body and cap may beintegrally formed. In other embodiments, a body and cap may be separatepieces that are joined by one or more fasteners. In the embodiment ofFIGS. 2-3, body 200 and cap 220 are separate pieces that are fastenedtogether using additional components of implant 100.

Embodiments of an implant may include provisions for anchoring theimplant into adjacent vertebral bodies. In some embodiments, an implantmay include one or more anchoring members. In the embodiment of FIGS.2-3, implant 100 includes a set of blades 240 that facilitate anchoringimplant 100 to adjacent vertebral bodies following insertion of implant100 between the vertebral bodies. Set of blades 240 may be furthercomprised of a first blade 241 and a second blade 242. Although theexemplary embodiments described herein include two blades, otherembodiments of an implant could include any other number of blades. Forexample, in another embodiment, three blades could be used. In anotherembodiment, four blades could be used, with two blades extending fromthe inferior surface and two blades extending from the superior surfaceof the implant. Still other embodiments could include five or moreblades. In yet another embodiment, a single blade could be used.

An implant with blades can include provisions for moving the blades withrespect to an outer structure of the implant. In some embodiments, animplant includes a blade actuating member that engages with one or moreblades to extend and/or retract the blades from the surfaces of theimplant. In the embodiment shown in FIGS. 2-3, implant 100 includes ablade actuating member 260. In some embodiments, blade actuating member260 is coupled to first blade 241 and second blade 242. Moreover, byadjusting the position of blade actuating member 260 within outerstructure 201, first blade 241 and second blade 242 can be retractedinto, or extended from, surfaces of implant 100.

An implant can include provisions for locking the position of one ormore elements of the implant. In embodiments where the position of ablade actuating member can be changed, an implant can include provisionsfor locking the actuating member in a given position, thereby alsolocking one or more blades in a given position. In the embodiment shownin FIGS. 2-3, implant 100 includes locking screw 280. In someembodiments, locking screw 280 can be used to lock blade actuatingmember 260 in place within implant 100, which ensures first blade 241and second blade 242 remain in an extended position.

Embodiments can include one or more fasteners that help attach a body toa cap. In some embodiments, pins, screws, nails, bolts, clips, or anyother kinds of fasteners could be used. In the embodiment shown in FIGS.2-3, implant 100 includes a set of pins 290 that help fasten cap 220 tobody 200. In the exemplary embodiments, two pins are used, includingfirst pin 291 and second pin 292. In other embodiments, however, anyother number of pins could be used. In another embodiment, a single pincould be used. In still other embodiments, three or more pins could beused.

Operation

The embodiments described herein provide an implant that can move from afirst position (the “insertion position”), which allows the implant tomaintain a low profile, to a second position (the “impaction position”or the “deployed position”), that deploys the blades and inserts theminto the proximal superior and inferior vertebral bodies. While theimplant is in the first (insertion) position, the blades of the devicemay be retracted within the body of the implant (i.e., the blades maythemselves be in a “retracted position”). In the second (deployed)position of the implant, the blades extend superiorly (or cranially) orinferiorly (or caudally) beyond the implant and into the vertebralbodies to prevent the implant from moving out of position over time.Thus, the blades themselves may be said to be in an “extended position”or “deployed position”. When the blades are deployed, the implantresists left to right rotation and resists flexion and/or extension. Itmay be appreciated that although the blades may approximately move invertical directions (i.e., the superior and inferior directions), theactual direction of travel may vary from one embodiment to another. Forexample, in some embodiments the blades may be slightly angled withinthe implant and may deploy at slight angles to a vertical direction (orto the inferior/superior directions).

FIGS. 4-7 illustrate several views of implant 100 in different operatingmodes or operating positions. Specifically, FIG. 4 is a schematicisometric view of implant 100 in an insertion position. FIG. 5 is aschematic lateral side view of implant 100 in the same insertionposition of FIG. 4. Referring to FIGS. 4-5, in the insertion positiondriven end 262 of blade actuating member 260 may be disposed distal toguide opening 222 of cap 220 (i.e., a portion of blade actuating member260 is disposed through guide opening 222). With implant 100 in theinsertion position, first blade 241 and second blade 242 are retractedwithin outer structure 201. Thus, as best seen in FIG. 5, neither firstblade 241 or second blade 242 extend outwardly (distally) from superiorside 130 or inferior side 140, respectively, of implant 100. In thisinsertion position, implant 100 has a compact profile and can be moreeasily maneuvered into place in the excised disc space between adjacentvertebrae.

FIG. 6 is a schematic isometric view of implant 100 in a deployedposition. FIG. 7 is a schematic lateral side view of implant 100 in thesame insertion position of FIG. 7. Referring to FIGS. 6-7, in thedeployed position driven end 262 of blade actuating member 260 may bedisposed proximally to guide opening 222 of cap 220 (i.e., the entiretyof blade actuating member 260 is disposed within implant 100). Withimplant 100 in the deployed position, first blade 241 and second blade242 are extended outwards from superior side 130 and inferior side 140,respectively, so as to be inserted into adjacent vertebral bodies.

In some embodiments, one or more blades could be deployed at a slightangle, relative to the normal directions on the superior and inferiorsurfaces of the implant. In some embodiments, one or more blades couldbe oriented at an angle between 0 and 30 degrees. In other embodiments,one or more blades could be oriented at an angle that is greater than 30degrees. In the exemplary embodiment shown in FIGS. 6-7, first blade 241and second blade 242 are both oriented at a slight angle from normalaxis 251. Specifically, first blade 241 forms a first angle 250 withnormal axis 251 and second blade 242 forms a second angle 252 withnormal axis 251. In one embodiment, first angle 250 and second angle 252are both approximately 15 degrees. Angling the blades in this way mayhelp keep first blade 241 and second blade 242 approximately centered inthe adjacent vertebrae upon deployment.

The extension of each blade could vary in different embodiments. In someembodiments, a blade could extend outwardly by a length between 0 and100% of the depth of an implant. In still other embodiments, combinedblade height could extend outwardly by a length between 100 and 130% ofthe depth of an implant. In the exemplary embodiment shown in FIGS. 6-7,first blade 241 and second blade 242 combined may be capable ofextending outwardly from implant 100 by an amount equal to 110% of thedepth of implant 100. This can be done while still keeping the bladesfully retracted within implant 100 since the blades are guided by tworobust parallel tracks in body 200 and also by angled cross channels inblade actuating member 260, thus constraining all six axes of motion. Inother embodiments, the combined blade height at deployment could be lessthan 100%. In one embodiment, the implant could be designed so that thecombined blade height is less than 10 mm to reduce the risk offracturing the adjacent vertebral bodies.

Blades and Blade Actuating Member

FIG. 8 is a schematic isometric view of first blade 241. First blade241, or simply blade 241, includes an outer edge 400, an inner edge 402,a first lateral edge 404 and a second lateral edge 406. These edges binda distal face 408 (i.e., a face oriented in the distal direction) and aproximal face 410 (i.e., a face oriented in the proximal direction).

In different embodiments, the geometry of a blade could vary. In someembodiments, a blade could have a substantially planar geometry suchthat the distal face and the proximal face of the blade are eachparallel with a common plane. In other embodiments, a blade could beconfigured with one or more bends. In some embodiments, a blade can havea channel-like geometry (ex. “C”-shaped or “S”-shaped). In theembodiment shown in FIG. 8, blade 241 has a U-shaped geometry withflanges. In particular, blade 241 a first channel portion 420, a secondchannel portion 422 and a third channel portion 424. Here, the firstchannel portion 420 is angled with respect to second channel portion 422at a first bend 430. Likewise, third channel portion 424 is angled withrespect to second channel portion 422 at second bend 432. Additionally,blade 241 includes a first flange 440 extending from first channelportion 420 at a third bend 434. Blade 241 also includes second flange442 extending from third channel portion 424 at fourth bend 436. Thisgeometry for blade 241 helps provide optimal strength for blade 241compared to other planar blades of a similar size and thickness, andallowing for greater graft volume.

In the exemplary embodiment, the outer edge 400 is a penetrating edgeconfigured to be implanted within an adjacent vertebral body. Tomaximize penetration, outer edge 400 may be sharpened so that blade 241has an angled surface 409 adjacent outer edge 400. Moreover, in someembodiments, first lateral edge 404 and second lateral edge 406 are alsosharpened in a similar manner to outer edge 400 and may act asextensions of outer edge 400 to help improve strength and penetration.

A blade can include provisions for coupling with a blade actuatingmember. In some embodiments, a blade can include a protruding portion.In some embodiments, the protruding portion can extend away from a faceof the blade and may fit within a channel in a blade actuating member.Referring to FIG. 8, blade 241 includes a protruding portion 450 thatextends from proximal face 410. Protruding portion 450 may generally besized and shaped to fit within a channel of blade actuating member 260(i.e., first channel 350 shown in FIG. 9). In particular, thecross-sectional shape may fit within a channel in blade actuating member260. In some cases, the cross-sectional width of protruding portion 450may increase between a proximal portion 452 and a distal portion 454allowing protruding portion 450 to be interlocked within a channel asdiscussed in detail below.

A protruding portion may be oriented at an angle on a blade so as to fitwith an angled channel in a blade actuating member. In the embodiment ofFIG. 9, protruding portion 450 may be angled with respect to inner edge402 such that blade 241 is vertically oriented within implant 100 whenprotruding portion 450 is inserted within first channel 350. In otherwords, the longest dimension of protruding portion 450 may form an angle459 with inner edge 402.

Although the above discussion is directed to first blade 241, it may beappreciated that similar principles apply for second blade 242. Inparticular, in some embodiments, second blade 242 may have asubstantially identical geometry to first blade 241.

FIG. 9 is a schematic side view of an embodiment of blade actuatingmember 260. An isometric view of blade actuating member 260 is alsoshown in FIG. 10. Referring to FIGS. 9 and 10, blade actuating member260 may include a driven shaft portion 320 and a blade engaging portion322. Driven shaft portion 320 further includes driven end 262.

In some embodiments, driven end 262 can include one or more engagingfeatures. For example, driven end 262 can include a threaded opening267, as best seen in FIG. 10. In some embodiments, threaded opening 267may receive a tool with a corresponding threaded tip. With thisarrangement, driven end 262 can be temporarily mated with the end of atool used to impact blade actuating member 260 and drive set of blades240 into adjacent vertebrae. This may help keep the driving tool anddriven end 262 aligned during the impact and reduce any tendency of thedriving tool to slip with respect to driven end 262. Using matingfeatures also allows driven end 262 to be more easily “pulled” distallyfrom implant 100, which can be used to retract blades 240, should it benecessary to remove implant 100 or re-position the blades.

Blade engaging portion 322 may comprise a superior surface 330, aninferior surface 332, a first side surface 334 and a second side surface336. Here, first side surface 334 may be an anterior facing side andsecond side surface 336 may be a posterior facing side. In otherembodiments, however, first side surface 334 could be a posterior facingside and second side surface 336 could be an anterior facing side.

A blade actuating member can include provisions for coupling with one ormore blades. In some embodiments, a blade actuating member can includeone or more channels. In the exemplary embodiment of FIG. 9, bladeengaging portion 322 includes a first channel 350 and a second channel352 (shown in phantom in FIG. 9). First channel 350 may be disposed infirst side surface 334 of blade actuating member 260 while secondchannel 352 may be disposed in second side surface 336 of bladeactuating member 260.

Each channel is seen to extend at an angle between superior surface 330and inferior surface 332 of a blade engaging portion 322. For example,as best seen in FIG. 9, first channel 350 has a first end 354 open alongsuperior surface 330 and a second end 356 open along inferior surface332. Moreover, first end 354 is disposed closer to driven shaft portion320 than second end 356. Likewise, second channel 352 includes opposingends on superior surface 330 and inferior surface 332, though in thiscase the end disposed at superior surface 330 is disposed further fromdriven shaft portion 320 than the end disposed at inferior surface 332.

In different embodiments, the angle of each channel could be selected toprovide proper blade extension for varying implant sizes. As usedherein, the angle of a channel is defined to be the angle formed betweenthe channel and a transverse plane of the blade actuating member. In theembodiment of FIG. 9, first channel 350 forms a first angle 372 withtransverse plane 370 of blade actuating member 260, while second channel352 forms a second angle 374 with transverse plane 370. In the exemplaryembodiment, first angle 372 and second angle 374 are equal to providebalanced reactive forces as the blades are deployed. By configuring theblades and blade actuating member in this manner, each blade is deployedabout a centerline (e.g., transverse plane 370) of the blade actuatingmember, which helps minimize friction and binding loads between theseparts during blade deployment. Additionally, the arrangement helpsprovide balanced reaction forces to reduce insertion effort andfriction.

In different embodiments, the angle of each channel could vary. In someembodiments, a channel could be oriented at any angle between 15 and 75degrees. In other embodiments, a channel could be oriented at any anglebetween 35 and 65 degrees. Moreover, in some embodiments, the angle of achannel may determine the angle of a protruding portion in acorresponding blade. For example, the angle 459 formed betweenprotruding portion 450 and inner edge 402 of blade 241 (see FIG. 8) maybe approximately equal to the angle 372 formed between first channel 350and transverse plane 370. This keeps the outer penetrating edge of blade241 approximately horizontal so that the degree of penetration does notvary at different sections of the blade.

As seen in FIG. 10, each channel has a cross-sectional shape thatfacilitates a coupling or fit with a corresponding portion of a blade.As an example, channel 350 has an opening 355 on first side surface 334with an opening width 390. At a location 357 that is proximal to opening355, channel 350 has a width 392 that is greater than opening width 390.This provides a cross-sectional shape for channel 350 that allows for asliding joint with a corresponding part of first blade 241. In theexemplary embodiment, first channel 350 and second channel 352 areconfigured with dovetail cross-sectional shapes. In other embodiments,however, other various cross-sectional shapes could be used that wouldfacilitate a similar sliding joint connection with a correspondinglyshaped part. In other words, in other embodiments, any geometry for ablade and a blade actuating member could be used where the blade andblade actuating member include corresponding mating surfaces of somekind.

In some embodiments, blade engaging portion 322 may be contoured at thesuperior and inferior surfaces to resist subsidence and allow maximumblade deployment depth. This geometry may also help to keep the bladeengaging portion 322 centered between vertebral endplates. As anexample, the contouring of superior surface 330 and inferior surface 332in the present embodiment is best seen in the enlarged cross-sectionalview of FIG. 10.

FIGS. 10-11 illustrate a schematic exploded isometric view and aschematic view, respectively, of blade actuating member 260 and set ofblades 240. Referring to FIGS. 10-11, protruding portion 450 of firstblade 241 fits into first channel 350. Likewise, protruding portion 455of second blade 242 fits into second channel 352.

Each channel may be associated with a first channel direction and anopposing second channel direction. For example, as best seen in FIG. 9,first channel 350 may be associated with a first channel direction 460that is directed towards superior surface 330 along the length of firstchannel 350. Likewise, first channel 350 includes a second channeldirection 462 that is directed towards inferior surface 332 along thelength of first channel 350.

With first protruding portion 450 of first blade 241 disposed in firstchannel 350, first protruding portion 450 can slide in first channeldirection 460 or second channel direction 462. As first protrudingportion 450 slides in first channel direction 460, first blade 241 movesvertically with respect to blade actuating member 260 such that firstblade 241 extends outwardly on a superior side of implant 100 (see FIGS.6-7). As first protruding portion 450 slides in second channel direction462, first blade 241 moves vertically with respect to blade actuatingmember 260 such that first blade 241 is retracted within outer structure201 of implant 100 (see FIGS. 4-5). In a similar manner, secondprotruding portion 455 of second blade 242 may slide in first and secondchannel directions of second channel 352 such that second blade 242 canbe extended and retracted from implant 100 on an inferior side (seeFIGS. 4-7). By using this configuration, blade actuating member 260propels both blades in opposing directions thereby balancing thereactive loads and minimizing cantilevered loads and friction on theguide bar.

As shown in the cross section of FIG. 11, the fit between each blade andthe respective channel in blade actuating member 260 may be configuredto resist motion in directions orthogonal to the corresponding channeldirections. For example, with first protruding portion 450 insertedwithin first channel 350, first blade 241 can translate along firstchannel direction 460 or second channel direction 462, but may not movein a direction 465 that is perpendicular to first channel direction 460and second channel direction 462 (i.e., blade 241 cannot translate in adirection perpendicular to the length of first channel 350).Specifically, as previously mentioned, the corresponding cross-sectionalshapes of first channel 350 and first protruding portion 450 are suchthat first protruding portion 450 cannot fit through the opening infirst channel 350 on first side surface 334 of blade actuating member260.

In some embodiments, each protruding portion forms a sliding dovetailconnection or joint with a corresponding channel. Using dovetail trackson the blade actuating member and corresponding dovetail features on theposterior and anterior blades allows axial movement along the angle ofinclination while preventing disengagement under loads encounteredduring blade impaction and retraction. For example, in FIG. 11, firstprotruding portion 450 forms a sliding dovetail joint with first channel350. Of course, the embodiments are not limited to dovetail joints andother fits/joints where the opening in a channel is smaller than thewidest part of a protruding portion of a blade could be used.

It may be appreciated that in other embodiments, the geometry of theinterconnecting parts between a blade and a blade actuating member couldbe reversed. For example, in another embodiment, a blade could compriseone or more channels and a blade actuating member could includecorresponding protrusions to fit in the channels. In such embodiments,both the protruding portion of the blade actuating member and thechannels in the blades could have corresponding dovetail geometries.

Body and Cap

FIG. 12 illustrates a schematic view of body 200. Body 200 may providethe posterior and anterior sides of outer structure 201, as well as atleast one lateral side of outer structure 201.

In some embodiments, the posterior and anterior sides of a body may bothhave a truss-like or lattice-like geometry. In other embodiments, theposterior and/or anterior sides could be configured as solid walls withone or more openings. In the exemplary embodiment shown in FIG. 12,posterior side 112 and anterior side 110 of body 200 have a truss-likegeometry comprised of diagonally oriented supports 500. Although aparticular pattern of supports is shown in FIG. 12, other embodimentscould have supports arranged in any other pattern, including anytruss-like and/or lattice-like patterns.

The configuration of supports 500 shown for the embodiment of FIG. 12may facilitate the manufacturing process. In particular, thisconfiguration may permit 3D Printing via laser or electron beam withminimal support structures by orienting the diagonal supports 500 morethan 45 degrees in relation to the build direction. Although theembodiment of FIG. 12 uses a truss-structure with openings betweensupports, other embodiments could include thin walls of material to fillin some of the openings between supports. Using an open truss designand/or a truss design with thin walls may help to improve visibility ofadjacent bony anatomy under X-ray fluoroscopy while still providingsufficient structural support and rigidity to withstand all testingrequirements and the clinical loading of an implant.

In other embodiments, a body may not have a truss or lattice-likegeometry. For example, an alternative design for a body 550 is shown inFIG. 15. As seen in FIG. 15, body 550 may be similar to body 200 in somerespects. However, rather than having a truss-like geometry, body 550uses a solid geometry with oval-shaped openings 552 on both the anteriorand posterior sides. Other embodiments, not pictured in the figures,include round or rectangular openings in otherwise solid geometry of theanterior, posterior, or lateral sides.

Embodiments can also include one or more blade retaining portions. Ablade retaining portion may receive any part of a blade, including oneor more edges and/or faces of the blade. In one embodiment, a bodyincludes blade retaining portions to receive the lateral edges of eachblade. As seen in FIG. 12, body 200 includes a first blade retainingportion 600 and a second blade retaining portion 602 on posterior side112. First blade retaining portion 600 is comprised of a first bladeretaining channel extending through the depth of body 200 that receivesfirst lateral edge 404 of first blade 241 (see FIG. 8). Likewise, secondblade retaining portion 602 is comprised of a second blade retainingchannel extending through the depth of body 200 that receives secondlateral edge 406 of first blade 241 (see FIG. 8). Body 200 also includesthird blade retaining portion 604 and fourth retaining portion 606 forreceiving the lateral edges of second blade 242. This configuration mayhelp maximize available bone graft volume within the implant since thelateral edges of the blades serve as tracks for translation.Specifically, this limits the need for additional track members on theblade that would take up additional volume in the implant. Furthermore,the arrangement of the retaining channels and the associated blade edgesresults in most of the volume of the retaining channels being filled bythe blade edges in the retracted position, which helps prevent any graftmaterial or BGPM from entering the retaining channels and inhibitingnormal blade travel.

FIGS. 13 and 14 illustrate isometric views of a distal side and aproximal side, respectively, of cap 220. Referring to FIGS. 13-14, cap220 includes one or more openings for engaging different parts ofimplant 100. For example, cap 220 may include a first pin hole 227 and asecond pin hole 228 that are configured to receive pin 291 and pin 292,respectively (see FIG. 3). Moreover, first pin hole 227 and second pinhole 228 (shown in FIGS. 13 and 14) of cap 220 may be aligned withcorresponding holes in the body.

As previously discussed, cap 220 may include an opening 224 to receive alocking screw or other fastener. Additionally, cap 220 may include guideopening 222 that receives a portion of blade actuating member 260. Insome embodiments, guide opening 222 may have a shape that matches thecross-sectional shape of a driven portion of a blade actuating member.In some embodiments, both guide opening 222 and driven shaft portion 320of blade actuating member 260 have rectangular cross-sectional shapes.This configuration may allow axial motion, but control rotational andangular loads that could result during blade impaction as exemplified inFIGS. 13-14.

In some embodiments, cap 220 may include attachment points for aninsertion instrument. For example, as seen in FIGS. 13-14, cap 220 mayinclude a first cavity 580 and a second cavity 582 that may receive theends of an insertion tool to improve the grip of the tool on implant 100during insertion into (or removal from) between the vertebrae of thespine.

As seen in FIG. 14, in some embodiments, cap 220 may also include acavity 570 for receiving a part of body 200. Specifically, cavity 570may receive a fastening end 576 of body 200 (see FIG. 12), whichincludes a pin receiving opening 578 shown in FIG. 12, so that fasteningend 576 can be retained within cavity 570 once second pin 292 has beeninserted in the assembled and un-deployed state shown in FIG. 2.

Three Point Attachment

FIG. 16 is a schematic top view of implant 100 in which attachmentsbetween the blades and other components of implant 100 are visible. FIG.17 is a schematic enlarged view of a region 650 of implant 100 includingfirst blade 241 and a portion of blade actuating member 260, in whichseveral attachment points are clearly visible.

Referring to FIGS. 16-17, implant 100 uses a three-point attachmentconfiguration for each of first blade 241 and second blade 242.Specifically, each blade is received along its lateral edges by twoblade retaining portions, and also coupled to blade actuating member 260using the dovetail connection described above. As seen in FIG. 16, firstlateral edge 404 of first blade 241 is received within the first bladeretaining channel of first blade retaining portion 600. Second lateraledge 406 of first blade 241 is received within a second retainingchannel of second blade retaining portion 602. Moreover, distal face 408of first blade 241 remains unattached to any other elements of implant100. Not only does first blade 241 remain unattached along distal face408, but the entirety of distal face 408 between first lateral edge 404and second lateral edge 406 is spaced apart from (i.e., not in contactwith) all other elements of implant 100. Further, second blade 242 islikewise attached at its lateral edges to corresponding blade retainingportions and also coupled to blade actuating member 260 using a slidingdovetail connection. Thus, first blade 241 and second blade 242 are heldin implant 100 using a three-point attachment configuration that maylimit unwanted friction on first blade 241 and second blade 242 duringimpaction. It may be appreciated that the fit between each blade andeach blade retaining channel may provide sufficient clearance to allowfor translation of the blades along the retaining channels. In otherwords, the fit may not be so tight as to impede movement of the lateraledges within the retaining channels.

In different embodiments, the cross-sectional geometry of channels inone or more blade retaining portions could vary. In some embodiments,the cross-sectional geometry could be rounded. In the embodiment shownin FIG. 17, blade retaining portion 600 is seen to have a rectangularblade retaining channel 620. This rectangular geometry for the bladetracks or channels and tolerance allows for precise axial travel withoutbinding from actuation ramp angular variations. Similarly, the remainingblade retaining portions of the embodiment of FIGS. 16-17 have similarrectangular shapes.

In some embodiments, the lateral edges of each blade may remain in thetracks or channels of each blade retaining portion while the blades areretracted to prevent bone graft material from restricting freedeployment of the blades.

Sliding Connection

Using an interlocking joint, such as a dovetail sliding joint, toconnect the blades and a blade actuating member helps prevent the bladesfrom decoupling from the blade actuating member during impact.Additionally, with an interlocking joint the blade actuating member canbe used to retract the blades.

FIGS. 18-21 illustrate several schematic views of implant 100 during animpact sequence (FIGS. 18-20) as well as during a step of retracting theblades (FIG. 21). In FIGS. 18-21, outer structure 201 of implant 100 isshown in phantom to better show blade actuating member 260, first blade241 and second blade 242. Also, each of FIGS. 18-21 include an enlargedcut-away view of a section of blade actuating member 260, first blade241 and second blade 242 to better illustrate the coupling between theseparts during actuation.

In FIG. 18, implant 100 is in the insertion position, with first blade241 and second blade 242 fully retracted within outer structure 201.Next, as seen in FIG. 19, an impacting force 700 is applied to drivenend 262 of blade actuating member 260. As blade actuating member 260 istranslated towards second lateral side 116 of implant 100, bladeactuating member 260 applies forces to first blade 241 and second blade242 along first channel 350 and second channel 352, respectively.Specifically, the orientation of first channel 350 is such that firstblade 241 is forced towards the superior side of implant 100. Likewise,the orientation of second channel 352 is such that second blade 242 isforced towards the inferior side of implant 100. Furthermore, theinterlocking connection between first protruding portion 450 and firstchannel 350 (as well as between second protruding portion 455 and secondchannel 352) means that both blades remain coupled to the motion ofblade actuating member 260 at all times. It should be noted that sinceboth blades are restricted from moving in a longitudinal direction(i.e., the direction of motion of blade actuating member 260), theresulting motion of each blade is purely vertical. Moreover, using thedovetail shaped protruding portions for each blade means the protrudingportions are both lifting at the center line to limit any cocking forceor rotational moments that could result in increased (friction)resistance to motion or binding of these moving parts.

Using this configuration, the forces deploying the blades are balancedthrough the blade actuating member 260 in order to minimize friction andbinding between driven shaft portion 320 and opening 222 in cap 220 (seeFIG. 3), which helps to guide blade actuating member 260 and keep itsmotion restricted to directions parallel to the longitudinal axis (seeFIG. 2).

In FIG. 20, implant 100 has been placed in the fully deployed position,with both first blade 241 and second blade 242 fully extended fromimplant 100. As seen in the enlarged cut-away view, both first blade 241and second blade 242 remain coupled with blade actuating member 260 whenimplant 100 is in the fully deployed position. Because of this coupling,the motion of blade actuating member 260 can be reversed to retractfirst blade 241 and second blade 242, as shown in FIG. 21.

Referring to FIG. 21, driven end 262 of blade actuating member 260 maybe pulled in an opposing direction to the motion shown in FIG. 19. Forexample, in some embodiments a delivery tool can be coupled to drivenend 262 using a threaded connector. Then, as the tip of the deliverytool is retracted a retracting or pulling force 710 may be applied todrive end 262. As blade actuating member 260 (and specifically, bladeengaging portion 322) is pulled towards first lateral side 114 ofimplant 100, blade actuating member 260 applies forces to first blade241 and second blade 242 along first channel 350 and second channel 352,respectively. Specifically, the orientation of first channel 350 is suchthat first blade 241 is forced towards the inferior side of implant 100.Likewise, the orientation of second channel 352 is such that secondblade 242 is forced towards the superior side of implant 100. Althoughnot shown, applying sufficient force at driven end 262 may result infull retraction of first blade 241 and second blade 242 so that implant100 is returned to the insertion position shown in FIG. 18.

Locking Screw

FIGS. 22-24 illustrate several schematic views of locking screw 280,according to an embodiment. Locking screw 280 includes a flanged head282 with a rounded segment 284 and a flat segment 286. Locking screw 280further includes a threaded body 288 and a rotation restricting groove289.

Rotation restricting groove 289 may include a first groove end 293 and asecond groove end 295 (see FIG. 23). As seen in FIGS. 22-24, rotationrestricting groove 289 may extend less than a full turn around thecircumference of threaded body 288.

FIGS. 25-26 illustrate schematic views of an implant, including anisometric view and an enlarged cross-sectional view taken near atransverse plane of implant 100. FIG. 25 is a schematic view of implant100 with locking screw 280 in an “unlocked” rotational position. In thisunlocked rotational position, locking screw 280 is rotated so that flatsegment 286 is aligned with an adjacent edge of opening 222, therebyallowing driven shaft portion 320 of blade actuating member 260 to passthrough opening 222 without impedance.

FIG. 26 is a schematic view of implant 100 with locking screw 280 in a“locked” rotational position. In this locked rotational position,locking screw 280 is rotated so that rounded segment 284 extends overopening 222 and blocks the passage of driven end 262 of blade actuatingmember 260 through opening 222. It may be appreciated that locking screw280 can only be placed in the locked rotational position once driven end262 has been pushed completely through opening 222 and is locatedproximally to locking screw 280.

As seen in FIG. 26, pin 291 may be disposed within rotation restrictinggroove 289 (see FIGS. 22-24) of locking screw 280. Moreover, rotationrestricting groove 289 may be sized and dimensioned to allow lockingscrew to be rotated between the locked and unlocked positions, but notrotated to the point of completely backing out of implant 100. Forexample, with pin 291 engaged in rotation restricting groove 289,locking screw 280 may only be rotated between a first rotationalposition where pin 291 is disposed against first groove end 293 and asecond rotational position where pin 291 is disposed against secondgroove end 295.

It may be appreciated that in some embodiments a blade actuating member(e.g., blade actuating member 260) may function to support adjacentvertebral bodies. This is can be accomplished by using a blade actuatingmember with a height similar to the height of the outer supportstructure so that the superior and inferior surfaces of the bladeactuating member may come into contact with the vertebral bodiesfollowing implantation. Since the blade actuating member functions as aload bearing structure within the implant, this may free up additionalspace in the implant otherwise occupied by additional supportstructures, thereby increasing the internal volume available for bonegraft or BGPMs.

Implant Dimensions

In different embodiments, the size of an implant could vary. In someembodiments, an implant could have any length. Embodiments could havelengths ranging from 40 mm to 60 mm. In some cases, a manufacturer couldprovide multiple implant options with lengths varying between 40 mm and60 mm in 5 mm increments. In some embodiments, an implant could have anyheight. Embodiments could have a height ranging from 8 mm to 16 mm. Insome cases, a manufacturer could provide implants with heights varyingfrom 8 mm to 16 mm in 2 mm increments. Embodiments could have widths(i.e., size along the posterior-anterior axis) of 18 mm, 22 mm, 26 mm aswell as other sizes.

Embodiments can also be constructed with various lordosis angles, thatis, angles of incline between the posterior and anterior sides.Embodiments could be configured with lordosis angles of 8, 15 and 20degrees, for example. In other embodiments, other lordosis angles couldbe used for an implant.

Alignment Features

Embodiments may optionally include one or more alignment features.Exemplary alignment features include, but are not limited to, windowsfor fluoroscopy positioning, windows for blade deployment validation,windows for aligning a blade actuating member with one or more blades,as well as various other kinds of alignment features. Referring to FIG.2, body 200 of implant 100 includes a central alignment window 209.Additionally, blade 241 includes an alignment window 297. Alignmentwindow 297 may align with central alignment window 209 when blade 241 isfully retracted. Moreover, blade actuating member 260 includes a firstalignment window 277 and a second alignment window 279. Window 277 andwindow 279 may align with the implant body center line when blade 241and blade 242 are fully deployed and retracted. One or more of thesewindows (i.e., central alignment window 209, first alignment window 277and/or second alignment window 279) may facilitate fluoroscopypositioning and may be used to confirm blade deployment. For example, insome cases, when first blade 241 and second blade 242 are fullydeployed, the blades may clear first alignment window 277 of bladeactuating member 260.

Some embodiments may also include one or more stroke limiting stops. Forexample, the embodiment of implant 100 shown in FIG. 2 includes a firststroke limiting stop 283 and second stroke limiting stop 287 on bladeactuating member 260. These stops may help prevent over travel of bladeactuating member 260. Specifically, stop 283 and stop 287 may contactthe internal surfaces of body 200.

Materials

The various components of an implant may be fabricated frombiocompatible materials suitable for implantation in a human body,including but not limited to, metals (e.g. titanium, titanium alloy,stainless steel, cobalt-chrome, or other metals), synthetic polymers(e.g. PEEK or PEKK), ceramics, and/or their combinations, depending onthe particular application and/or preference of a medical practitioner.

Generally, the implant can be formed from any suitable biocompatible,non-degradable material with sufficient strength. Typical materialsinclude, but are not limited to, titanium, biocompatible titanium alloys(e.g. Titanium Aluminides (including gamma Titanium Aluminides),Ti₆—Al₄—V ELI (ASTM F 136 and ASTM F 3001), or Ti₆—Al₄—V (ASTM F 1108,ASTM F 1472, and ASTM F 2989) and inert, biocompatible polymers, such aspolyether ether ketone (PEEK) (e.g. PEEK-OPTIMA®, Invibio Inc, Zeniva®,Solvay Inc., or others). Optionally, the implant contains a radiopaquemarker to facilitate visualization during imaging when constructed ofradiolucent biomaterials.

In different embodiments, processes for making an implant can vary. Insome embodiments, the entire implant may be manufactured and assembledvia traditional and CNC machining, injection-molding, cast or injectionmolding, insert-molding, co-extrusion, pultrusion, transfer molding,overmolding, compression molding, 3-Dimensional (3-D) printing,dip-coating, spray-coating, powder-coating, porous-coating, milling froma solid stock material and their combinations.

In one embodiment, body 200 may be produced by Direct Metal LaserSintering (DMLS) using powder Ti-6Al-4V ELI, and then traditional or CNCmachined in specific locations to precise dimensions. Moreover, in oneembodiment, blade actuating member 260, first blade 241, second blade242, cap 220, pins 290 and locking screw 280 may also be made of amaterial including titanium.

Implantation

Some embodiments may use a bone growth promoting material, includingbone graft or bone graft substitute material. As used herein, a “bonegrowth promoting material” (BGPM) is any material that helps bonegrowth. Bone growth promoting materials may include provisions that arefreeze dried onto a surface or adhered to the metal through the use oflinker molecules or a binder. Examples of bone growth promotingmaterials are any materials including bone morphogenetic proteins(BMPs), such as BMP-1, BMP-2, BMP-4, BMP-6, and BMP-7. These arehormones that convert stem cells into bone forming cells. Furtherexamples include recombinant human BMPs (rhBMPs), such as rhBMP-2,rhBMP-4, and rhBMP-7. Still further examples include platelet derivedgrowth factor (PDGF), fibroblast growth factor (FGF), collagen, BMPmimetic peptides, as well as RGD peptides. Generally, combinations ofthese chemicals may also be used. These chemicals can be applied using asponge, matrix or gel.

Some bone growth promoting materials may also be applied to animplantable prosthesis through the use of a plasma spray orelectrochemical techniques. Examples of these materials include, but arenot limited to, hydroxyapatite, beta tri-calcium phosphate, calciumsulfate, calcium carbonate, as well as other chemicals.

A bone growth promoting material can include, or may be used incombination with a bone graft or a bone graft substitute. A variety ofmaterials may serve as bone grafts or bone graft substitutes, includingautografts (harvested from the iliac crest of the patient's body),allografts, demineralized bone matrix, and various synthetic materials.

Some embodiments may use autograft. Autograft provides the spinal fusionwith calcium collagen scaffolding for the new bone to grow on(osteoconduction). Additionally, autograft contains bone-growing cells,mesenchymal stem cells and osteoblast that regenerate bone. Lastly,autograft contains bone-growing proteins, including bone morphogenicproteins (BMPs), to foster new bone growth in the patient.

Bone graft substitutes may comprise synthetic materials includingcalcium phosphates or hydroxyapatites, stem cell containing productswhich combine stem cells with one of the other classes of bone graftsubstitutes, and growth factor containing matrices such as INFUSE®(rhBMP-2-containing bone graft) from Medtronic, Inc.

It should be understood that the provisions listed here are not meant tobe an exhaustive list of possible bone growth promoting materials, bonegrafts or bone graft substitutes.

In some embodiments, BGPM may be applied to one or more outer surfacesof an implant. In other embodiments, BGPM may be applied to internalvolumes within an implant. In still other embodiments, BGPM may beapplied to both external surfaces and internally within an implant.

While various embodiments have been described, the description isintended to be exemplary, rather than limiting, and it will be apparentto those of ordinary skill in the art that many more embodiments andimplementations are possible that are within the scope of theembodiments. Although many possible combinations of features are shownin the accompanying figures and discussed in this detailed description,many other combinations of the disclosed features are possible. Anyfeature of any embodiment may be used in combination with, orsubstituted for, any other feature or element in any other embodimentunless specifically restricted. Therefore, it will be understood thatany of the features shown and/or discussed in the present disclosure maybe implemented together in any suitable combination. Accordingly, theembodiments are not to be restricted except in light of the attachedclaims and their equivalents. Also, various modifications and changesmay be made within the scope of the attached claims.

What is claimed is:
 1. An implant, comprising: a body, the body having afirst axis; a blade, the blade having a retracted position in the bodyand an extended position where the blade extends outwardly from thebody; a blade actuating member that can translate through the body indirections parallel to the first axis; the blade actuating memberincluding a channel, wherein the channel extends between a superiorsurface and an inferior surface of the blade actuating member, andwherein the channel defines a first channel direction and an opposingsecond channel direction; the blade including a protruding portionconfigured to fit within the channel; wherein when the blade actuatingmember is moved in a first direction along the first axis, theprotruding portion follows the channel in the first channel directionand the blade moves towards the extended position; and wherein when theblade actuating member is moved in a second direction opposite the firstdirection, the protruding portion follows the channel in the secondchannel direction and the blade moves towards the retracted position;wherein the blade has an outer edge, an inner edge disposed opposite theouter edge, a first lateral edge, and a second lateral edge disposedopposite the first lateral edge; and wherein the blade is only incontact with the body along the first lateral edge and the secondlateral edge.
 2. The implant according to claim 1, wherein the channeland the protruding portion of the blade form a sliding joint between theblade actuating member and the blade, and wherein the sliding jointallows the blade to move relative to the blade actuating member alongthe first channel direction or the second channel direction and whereinthe sliding joint prevents the blade from moving in a directionperpendicular to the first channel direction or the second channeldirection.
 3. The implant according to claim 1, wherein the channel andthe protruding portion together form a mating connection between theblade actuating member and the blade.
 4. The implant according to claim3, wherein the protruding portion has a dovetail cross-sectional shape,wherein the channel has a dovetail cross-sectional shape, and whereintogether the channel and the protruding portion form a sliding dovetailjoint.
 5. The implant according to claim 1, wherein the body includes afirst retaining channel to hold the first lateral edge and wherein thebody includes a second retaining channel to hold the second lateraledge.
 6. The implant according to claim 5, wherein the first retainingchannel and the second retaining channel are oriented at a nonzero anglewith the first axis.
 7. An implant, comprising: a body, the body havinga first axis; a blade, the blade having a retracted position in the bodyand an extended position where the blade extends outwardly from thebody; the blade having an outer edge, an inner edge disposed oppositethe outer edge, a first lateral edge, a second lateral edge disposedopposite the first lateral edge, a distal face, and a proximal face;wherein the first lateral edge of the blade and the second lateral edgeof the blade are in contact with the body; a blade actuating member thatcan translate through the body in directions parallel to the first axis;wherein a portion of the proximal face of the blade is in contact withthe blade actuating member; wherein the distal face of the blade isdisposed away from the body; and wherein the blade actuating member canmove the blade between the retracted position and the extended position;wherein the body includes a first retaining channel and a secondretaining channel disposed opposite the first retaining channel, whereinthe first lateral edge of the blade is received in the first retainingchannel, and wherein the second lateral edge of the blade is received inthe second retaining channel.
 8. The implant according to claim 7,wherein the blade is only in contact with the body along the firstlateral edge and the second lateral edge.
 9. The implant according toclaim 7, wherein the blade has a first bend where a first blade portionand a second blade portion meet at a nonzero angle.
 10. The implantaccording to claim 7, wherein the blade actuating member is coupled tothe blade by a sliding joint.
 11. The implant according to claim 10,wherein the blade actuating member includes a channel and wherein theblade includes a protruding portion that fits within the channel. 12.The implant according to claim 11, wherein the channel in the bladeactuating member and the protruding portion together form a slidingdovetail joint.
 13. The implant according to claim 12, wherein thechannel in the blade actuating member extends diagonally on a side ofthe blade actuating member.
 14. The implant according to claim 7,wherein the blade actuating member includes an alignment window forindicating when the blade has been fully deployed.
 15. An implant,comprising: an outer structure, the outer structure having a first axis;a blade, the blade having a retracted position in the outer structureand an extended position where the blade extends outwardly from theouter structure; a blade actuating member that can translate through theouter structure in directions parallel to the first axis; wherein theblade actuating member is coupled to the blade and can move the bladebetween the retracted position and the extended position; the outerstructure including a first end having a threaded opening having a firstlongitudinal axis and a guide opening adjacent the threaded opening andhaving a second longitudinal axis that is non-aligned with the firstlongitudinal axis, the guide opening receiving a driven end of the bladeactuating member; a locking screw secured within the threaded opening;wherein the locking screw can be rotated between an unlocked rotationalposition in which the driven end of the blade actuating member can passthrough the guide opening and a locked rotational position, in which thedriven end of the blade actuating member is prevented from movingthrough the guide opening.
 16. The implant according to claim 15,wherein the locking screw includes a threaded portion and a flangeportion, wherein the flange portion includes a rounded segment and aflat segment.
 17. The implant according to claim 16, wherein the flatsegment is aligned with an edge of the guide opening in the unlockedrotational position and wherein the rounded segment is disposed over theedge of the guide opening in the locked rotational position.
 18. Theimplant according to claim 15, wherein: the outer structure comprises abody and a cap; wherein the implant further includes a pin that extendsthrough the body and the cap and helps secure the body to the cap;wherein a threaded portion of the locking screw includes a rotationconstraining groove; wherein the rotation constraining groove includes afirst groove end and a second groove end; and wherein the rotationconstraining groove extends less than one full rotation around thecircumference of the threaded portion.
 19. The implant according toclaim 18, wherein the pin extends partially through the threaded openingof the outer structure and engages the rotation constraining groove. 20.The implant according to claim 19, wherein the locking screw isconstrained to rotate between a first rotational position and a secondrotational position, the first rotational position being a positionwhere the pin is disposed adjacent the first groove end and the secondrotational position being a position where the pin is disposed adjacentthe second groove end.